Underfeed fire pot



Jan. 25, 1938. A. E. PAIGE 2,106,621

UNDERFEED FIRE POT Filed April 8, 1937 2 Shets-Sheet 1 Jan. 25, 1938. A. E. PAIGE 2,106,621

UNDERFEED FIRE POT Filed April 8, 1937 2 Sheets-Sheet 2 HEM Ill] I'lll lNVE/VTOE:

Patented Jan. 25, 1938 UNITED STATES PATENT OFFICE I militia M I Arthur a. at, Philadelphia, Paw Applicatiozt, 81:0. 135,

My invention may be advantageously employed in automatic stokers, adapted for burning anthracite coal of small sizes, of the typewherein the fire pot structure includes a hollow base for re- 5 ception of air, a tubular grate extending above said base and means for forcing the fuel upwardly into said grate. My invention relates particularly to an improvement in the structure of such a grate. As hereinafter described, such a m grate includes a circular series of sectoral grate bars, which are of the same pattern; each bar being imperforate and the opposite edges of each bar being so formed that they are complementary to form air passages between the bars from said 5 base :to the interior of the grate.

My invention includes the various novel features of construction andarrangement hereinafter more definitely specified.

In said drawings; Fig. I is a plan view of a fire pot structure for such an automatic stoker.

Fig. 11 is a diametrical vertical sectional view of said structure, taken on the line 11,- II in Fi I.

Fig. III is an elevation of the right hand side of the structure shown in Fig. I.

Fig. IV is a vertical sectional view of said structure taken on the line TV, IV in Fig. I.

Fig. V is a fragmentary circumferential sectional view of adjoining bars in said grate.

Figs. VI and VII are respectively top and bottom views of the grate bar shown at the left hand side of Fig. IV. v

Fig. VIII is a bottomview of-a modified form of grate bar. r p

Fig. IX is a fragmentarycircumferential sectional view, similar .to Fig. V but showing said modified form-of bars. I

In said s; the hollow base I, is adapted to receiveia supplyof air, through the pipe 2 and o inlet 2', conveniently from an electrically driven blower. The fuel conduit includes the pipe 3 and the elbow 4 which has the inlet 4' extending beneath one side of said base I. Said elbow is secured to said base by bolts I' and has the upwardly extending cylindrical flange 6 and horizontal flange 1;comprising an annular support for the lower ends of radial grate bars 8, which fit between said flanges. The upper ends of said bars 8 are supported by the rim 9 of said base I.

The top ring plate III, secured to said rim of the base I by bolts II, prevents displacement of the upper ends of said bars 8 and affords a fiat top surface from which the ash, resulting from combustion of fuel on said grate, is discharged outward by any means for underfeeding fuel into 'away from the air passages I3, so as not to clog said grate. Such means may include the reciprocatory conveyer plunger 5 which has wedge projections 5' adapted to engage comminuted coal and is actuated by the electric motor which oper ates the blower.

inclined surface I6, intermediate of the opposite edges I4 and I5 of each bar 8 and thence inwardly to the interior of said grate, in small streams which penetrate the interstices between the particles offuel and insure completecombustion of the latter.

Each of said grate bars 8 has an outwardly extending radial rib I8 on the outer surface of the bar, separating the corrugated edge thereof from the opposite complementary edge thereof. Said ribs extending outwardly into the air space between the outer wall 9 of the air base I and the annular support 6, I for the lower ends of the grate bars deflect the air from the main stream, circulating in said base, so as to equally dis- 3o tribute the air throughout the area of the grate.

It is to be particularly noted that the projection of the corrugations I2 outwardly from'said bars 8, insures that the fly ash shall gravitate the latter. Moreover, the extension of said pas- 35 sages circumferentially in the grate insures that the incoming air shall be properly heated by contact with the outer grate surface before it comes in contact with the fuel, and directed vortically, 4o vertically, in the grate.

Although the structure above described is such that the air is driven counter-clockwise in the base I and clockwise in the grate owing to the deflecting effect of said radial ribsIB on the bars 45 8; the ribs may be omitted and grate bars formed so that the air is directed counter-clockwise in the grate. Such barsare shown at 20 in Figs. VIII and IX and, as shown in Fig. VlII the corrugations 2| thereon are on the opposite edge 50 to that upon which they are presented on the bars 8. The edge 22 on each of said bars 20, which overlaps the corrugations 2I on the adjoining bar is also preferably curved outwardly at its outer'edge so as to facilitate the passage 55 of the air from the base I through the passageways 23 between such bars as shown in Fig.1!

It is characteristic of both of said forms of grate bars, that the air is directed into the grate and through the fuel therein in vortical streams, all in the same direction circumferentially with respect to the axis of the grate, as distinguished from grates of the prior art through which air is directed in streams which are opposed to .each other. The vertical currents induced by my invention facilitate the mixture of the air with the combustible gases from the fuel and combustion of the latter. a

Although, for simplicity of construction, I prefer to make all the bars in a grate of the same pattern, with their cir'cumferentially opposite edges complementary to each other, of course bars having such outwardly projecting corrugations, partly forming air passages, may have other means complementary thereto to complete the air passages.

As a small percentage of the fiy ash inevitably falls into the base I; I provide the latter with the bottom outlet 24 having the door 25 hingedly connected with said base, by the pintle 28. Said door has the pendent lug 25' to which the end of the rod 21 is pivotally connected. Saidrod is continually stressed to close said door 25 by means of a spring attached to its distal end, not shown, so that manual traction upon said rod in the direction of the arrow in Fig. I swings said door downwardly and opens said outlet 24 so that the circular current of air in said base discharges any ash from the bottom thereof through said outlet 24 so that it may be carried up the chimney by the draft in the furnace in which the grate is located.

However, I do not desire to limit myself to the precise details of construction and arrangement herein set forth, as it is obvious that various modifications may be made therein without departing from the essential features of my invention as defined in the appended claims.

I claim:

1. A sectoral grate bar, having opposite substantially radial edges and a convex fuel supporting surface for presentation toward the interior of an annular grate, formed of a plurality of such bars; said bar having at one edge thereof, a series-of corrugations extending circumferentially with respect to said grate; the opposite edge of said bar being offset to overlap the corrugated surface of the adjoining bar; whereby said bar has its opposite edges radially spaced and complementary to form air passages between said corrugations. I

2. A sectoral grate bar, having opposite substantially radial edges and an inclined fuel supporting surface for presentation toward the interior of an annular grate, formed of a plurality of such bars; said bar having at one edge thereof, a series of corrugations extending circumferentially with respect to said grate; the opposite edge of said bar being shaped to overlap and complement the corrugated surface of the adjoining bar in the formation of air passages between said bars; and an outwardly extending radial rib on the outer surface of said bar, separating the corrugated edge thereof from the complementary edge thereof.

3. In an automatic stoker; a fire pot structure including a hollow annular base for reception of air; an annular support in said base for the lower ends of grate bars; an annular support in said base for the upper ends of grate bars and having a larger diameter than said first support; and an annular grate of upwardly outwardly flaring configuration including a circular series of sectoral grate bars having circumferentially overlapping edges forming air passages between said bars, all extending tangentially in the same direction with respect to the circular configuration of the grate; whereby, air supplied to the interior of said base escapes through the grate to the interior thereof in vortical, vertical streams.

, ARTHUR E. PAIGE. 

